The male name Þórarinn is traditionally Þórarni in the dative. In addition to the usual dative form, four innovative forms have been used, Þórarin, Þórarini, Þórarinum and Þórarininum. Here, att empts are made to explain how these forms emerged. Þórarinand Þórarini have their counterparts in the infl ection of personal names, e.g. Benedikt(dat.) and Auðuni (dat.), and are apparently due to proportional analogy. Þórarinumis a surprising form and may be due to proportional analogy and non-proportional analogy (rhyming formation), the two types even working in harmony. Þórarininumis also unexpected and may be due to other non-proportional types of analogy (blending/contamination or folk etymology).